PR: add support for equation labelling and referencing (more mathjax compatibility)

[qnxor]

As seen here: KaTeX/KaTeX#2003 (comment)

I enabled it in the Discourse code too as seen in the commit. This adds support for \tag, \label, \ref, \eqref so equations can be labeled and referenced (references are clickable too). This is another feature that Katex disables by default. Enabling it brings the Katex implementation in DIscourse more inline with Mathjax. My previous PR added support for persistent macros.

Tested and working in latest Discourse stable.

@pmusaraj

[pmusaraj]

Thanks @qnxor, can you fix the linting error please?

[qnxor]

I would but it gives no details, it's from your prettier which just exits with a 1 code giving no error details. Not sure what is it it doesn't like as the code style I used matches the rest. Have a look and let me know.

[pmusaraj]

It's the assets/javascripts/initializers/discourse-math-katex.js file. You need to:

• run yarn install at the root of the plugin repository
• run yarn run prettier --write assets/javascripts/initializers/discourse-math-katex.js

[qnxor]

~$ cd discourse-math
~/discourse-math$ yarn install
00h00m00s 0/0: : ERROR: [Errno 2] No such file or directory: 'install'

Never bothered with yarn or prettier in the past myself (edit: I could install only prettier from node manually without yarn?)

[pmusaraj]

Looks like you have a more recent yarn version than what we expect (we use Yarn 1, you probably have version 2+, you can check the exact version via yarn --version.

[qnxor]

$ yarn --version
0.32+git

I'm on Ubuntu 22.04 with standard apt repos (no ppas)

About your suggested change, it should work and it's equivalent, but I like to keep initializer code separated from the iterator, otherwise one would argue you should do away with the decorate() function entirely and bring its body into the katex() caller. With your suggestion, you now have per-elem processing in both decorate() and katex(), which I'd vote against.

I'll install prettier manually to output something your linter won't complain about.

[qnxor]

Fixed into a new commit. Turns out prettier doesn't like single quoted strings. You can run the checks again and approve it.

[qnxor]

About your suggested change, it should work and it's equivalent,

@pmusaraj sorry, your suggestion is actually not equivalent and it won't work since elem is an argument of the each() handler, it doesn't exist in the parent scope. I marked it as resolved by mistake, I'm not sure if your edit got through; it shouldn't since i mad a new commit after it so if you accept the newest commit then it should all be fine.

My code is also (marginally) more efficient as it doesn't create a new object on every call to decorate() like the original code was doing.

[pmusaraj]

Thanks @qnxor, merging.